This invention relates to a method of detecting damage, such as impact damage which may occur to a structural member in use, the structural member being a part of a working arm, e.g. a boom or boom section of a working apparatus such as load handling machine of the kind which in use may travel over the ground to carry loads. Examples of such machines are so called telescopic loaders in which the boom includes a plurality of telescopically extendible and retractable sections, although the invention may be applied to other working apparatus.
Particularly where such booms are made of materials other than metal, which readily deform upon impact with sufficient force, the boom may not readily visually reveal damage, e.g. when impacted, even though such damage may well be critical to the safe continued use of the machine.